AGRONOMIC PERFORMANCE OF TALL VERSUS SHORT SEMIDWARF LINES OF SPRING WHEAT

Plant height and grain yield have been positively associated in many studies of wheat (Triticum aestivum L.). The introduction of semidwarf genes changed this relationship by enhancing grain yield as well as reducing plant height. A strategy to select for tall dwarfs was proposed to exploit the positive correlation between yield and plant height observed without semidwarf genes, yet use the advantages of semidwarfism. The objective of this study was to evaluate the proposed model in spring wheat by comparing the yield potential of tall vs. short semidwarf lines. Randomly derived semidwarf lines from four crosses were assigned to tall and short groups based on their plant height. These groups were tested in a total of five environments in Minnesota from 1986 through 1988. The selected trait, plant height, differed between groups in all crosses. The tall-line group did not differ from the short-line group for grain yield within or across environments for Crosses 1, 2, and 3. The tall-line group of Cross 4 exceeded the short-line group for grain yield in the two higher yielding environments, and across environments. The tall group was later in days to head in Crosses 1 and 4. Correlations among traits were generally nonsignificant. The lack of a positive association between plant height and grain yield in three of four crosses indicated that sufficient evidence was not found to support the application of the tall dwarf model in this hard red spring wheat germplasm.